Comparison with existing solutions

Here is comparison with UUCP
(Unix to Unix copy), FTN (FidoNet Technology Networks) and SMTP
(because it is also store-and-forward solution).

UUCP

FTN

NNCP

SMTP

Ease of setup

Medium

Hard

Easy

Hard

Mail transmission

Yes

Yes

Yes

Yes

News transmission

Yes

Yes

No

No

File transmission

Yes

Yes

Yes

No

Chunked files

No

Yes

Yes

No

Remote command execution

Yes

No

No

No

Resumable downloads

Yes

Yes

Yes

No

Packets prioritizing

Yes

No

Yes

No

Mail compression

No

Yes

Yes

No

SMTP integration

Yes

No

Yes

N/A

Push/poll

Both

Both

Both

Push

DTN

Yes

Yes

Yes

No

Intended network size

Dozens

Global

Dozens

Global

Routing

Manual/static

Federated

Manual/static

Federated

PSTN support

Yes

Yes

Possible

No

Anonymous peers

Yes

No

No

Yes

Peers authentication

PAP

PAP/CHAP

public-key

No

Packets encryption

No

No

Yes

No

Metadata privacy

No

No

Yes

No

Packets integrity check

No

No

Yes

No

Sneakernet friendliness

No

No

Yes

No

Ease of setup

UUCP can be setup rather easily with few configuration files
and few lines in each of them. But you have to add some encryption
and authentication overlay for securing you data transmission.

FTN is hard to setup because it is totally different world of
software comparing to Unix one. Even mail editor will be something
like GoldEd, not an ordinary email client. Moreover, there is no
out-of-box encryption and strong authentication involved.

SMTP does not know anything about news, NNTP and so forth. Neither
does NNCP, because they are not used very much nowadays.

File transmission

SMTP could transfer files only Base64-encoding them – this is very
inefficient.

Chunked files

FTN software can automatically split huge files on smaller chunks,
to reassemble it on the destination node. NNCP also supports
that feature, especially important when dealing with
small capacity removable storage devices.

Packets prioritizing

UUCP and NNCP will push higher priority ("grade" in UUCP
terminology) packets first. You mail will pass, even when many
gigabytes files are queued in parallel.

SMTP integration

Mail servers like Postfix offers
documentation and configuration file examples how to use it with
UUCP. Exim and
Sendmail could be
integrated with UUCP rather easily too. For using NNCP, just replace
UUCP commands with NNCP ones.

Push/poll

With SMTP, you have to wait online when remote peers will push you
the messages. There are extensions to the protocol allowing
poll-model, but they are not used everywhere. This is very important
to be independent from specified model and be able to exchange the
data with possibility you have.

SMTP will drop messages that can not be delivered for a long time
(several days). Others are tolerant for the long delays.

Routing

UUCP and NNCP does not known nothing about routing. You have to
explicitly tell how to send (what hops to use) packets to each node.

PSTN support

UUCP and FidoNet always have been working with modems out-of-box.
Only many years later they gained support for working over TCP/IP
connections. SMTP works only over TCP/IP. NNCP currently has only
TCP daemon, but nothing prohibits using of another 8-bit aware
online transport.

Anonymous peers

NNCP and FTN are friend-to-friend networks exclusively. This is very
secure and mitigates many possible man-in-the-middle (MitM) and
Sybil attacks.

Sneakernet friendliness

No one, except NNCP, supports data exchanging via removable storages
likes flash drives, CD-ROMs, tapes and hard drives out-of-box. It
can be emulated for many FTN software, by manually copying files in
its inbound/outbound directories. But UUCP and SMTP software
requires more manual work to do so.